The development of photoredox reactions of aryloxy-amides for the generation of amidyl radicals and their use in hydroamination-cyclization and N-arylation reactions is reported. Owing to the ease of single-electron-transfer reduction of the aryloxy-amides, the organic dye eosin Y was used as the photoredox catalyst, which results in fully transition-metal-free processes. These transformations exhibit a broad scope, are tolerant to several important functionalities, and have been used in the late-stage modification of complex and high-value N-containing molecules.

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Carbon dioxide (CO 2) is an attractive one-carbon (C1) building block in terms of sustainability and abundance. However, its low reactivity limits applications in organic synthesis as typically high-energy reagents are required to drive transformations. Here, we present a redox-neutral C−H carboxylation of arenes and styrenes using a photocatalytic approach. Upon blue-light excitation, the anthrolate anion photocatalyst is able to reduce many aromatic compounds to their corresponding radical anions, which react with CO 2 to afford carboxylic acids. High-throughput screening and computational analysis suggest that a correct balance between electron affinity and nucleophilicity of substrates is essential. This novel methodology enables the carboxylation of numerous aromatic compounds, including many that are not tolerated in classical carboxylation chemistry. Over 50 examples of C−H functionalizations using CO 2 or ketones illustrate a broad applicability. The method opens new opportunities for late-stage C−H carboxylation and valorization of common arenes. File list (2) download file view on ChemRxiv C-H Carboxylation.pdf (657.79 KiB) download file view on ChemRxiv C-H Carboxylation-SI.pdf (3.04 MiB)

In the last decade, visible‐light photoredox catalysis has evolved into a versatile tool in organic synthesis. However, most reports have used homemade photoreactors in their design and optimisation of new methods, complicating the reproducibility of some transformations. To improve reproducibility and efficiency, laboratory photoreactors have been developed and commercialized. Herein we report a comparison of four commercially available photoreactors in six mechanistically distinct photoredox reactions focusing on the difference in product yields and kinetics as well as the factors which lead to these differences, including reaction temperature and light intensity.

Arylamines constitute the core structure of many therapeutic agents, agrochemicals, and organic materials. The development of methods for the efficient and selective construction of these structural motifs from simple building blocks is desirable but still challenging. We demonstrate that protonated electron‐poor O‐aryl hydroxylamines give aminium radicals in the presence of Ru(bpy)3Cl2. These highly electrophilic species undergo polarized radical addition to aromatic compounds in high yield and selectivity. We successfully applied this method to the late‐stage modification of chiral catalyst templates, therapeutic agents, and natural products.

Visible-light photoredox catalysis enables the synthesis of biologically relevant isoxazolines and isoxazoles from hydroxyimino acids. The process shows broad functional group compatibility and mechanistic and computational studies support a visible-light-mediated generation of nitrile oxides by two sequential oxidative single electron transfer processes.

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms Supporting Information PlaceholderAbstract: A concise synthesis of stereodefined C-substituted morpholines, piperazines, azepines and oxazepines in moderate to excellent yields (27% to 75%) is reported by reaction of 1,2-or 1,3-amino alcohol/1,2-or 1,3-diamine with an α-phenylvinylsulfonium salt. High levels of regio-and diastereoselectivity (from 2:1 to >20:1) are observed through judicious choice of base (Cs 2 CO 3 ), and solvent (CH 2 Cl 2 ). Reactions are performed at ambient temperature and open to air and do not require anhydrous solvent. The deprotection of the N-sulfonamide protecting groups (N-Ts and N-Ns) is also demonstrated. Factors affecting regio-and diastereocontrol are discussed.

A visible-light-mediated synthesis of 5-methylenepyrrolidinones is reported. This constitutes to the first reported